Circularly-polarized light is used in various fields, including imaging/photography, microscopy, biology, data storage, astronomy, communication, and quality inspection. A circular polarizer can be used to create circularly-polarized light. Circular polarizers can be made by thin film technologies. A disadvantage of thin film circular polarizers is a narrow wavelength band of effective performance (e.g. typically <200 nm bandwidth). Circular polarizers can be expensive and complicated to manufacture. It would be beneficial to provide a circular polarizer capable of effectively polarizing a large bandwidth of light, and that could be manufactured relatively simply and inexpensively.
In some optical systems, light can reflect off of optical components. This reflected light can cause problems in some optical systems, such as for example lasers and image projectors. An optical isolator can be used to remove this reflected light from the optical system. Present optical isolators are usually manufactured using thin films, can have a narrow wavelength band of effective performance, can have a low laser-damage threshold, and can be expensive. It would be beneficial to provide a low-cost, high laser-damage threshold, broadband optical isolator with improved ability to withstand laser light.